Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations indicate readOnlyHint=true, idempotentHint=false, and destructiveHint=false, so no safety contradictions. Description adds useful context: it returns specific engine fields, allows fuzzy matching, and notes it's part of an add-on, which helps the agent understand scope and potential access limitations. This goes beyond the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is concise (about three sentences) and front-loads the core purpose and output fields. It efficiently conveys identification methods and the add-on note without fluff. Every sentence contributes value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's moderate complexity, an output schema exists, and annotations cover safety, the description is mostly complete. It specifies output fields and identification methods. It could benefit from noting that no parameters are required, but that's inferrable. Minor gap, so 4 is suitable.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema covers all 4 parameters with descriptions. The description adds no extra semantics beyond what's in the schema, but the schema is quite complete. Baseline 3 is appropriate given 100% coverage.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Description clearly states 'Return the main-engine specification for a vessel' and enumerates the specific fields (designation, builder, propulsion, MCO). It distinguishes itself from siblings like intel_class and intel_info by focusing on engine specs, and mentions the add-on context, ensuring clear differentiation.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Description implies usage: 'Identify the vessel by imo or name' and mentions fuzzy matching, but it doesn't explicitly state when to use this tool over other intel tools or exclude alternatives. It provides minimal guidance on choice between imo vs name. Could be improved by noting typical use cases, but it's adequate.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.